The second variant, the attachment of additional vertical shutter button, the camera is much larger, but still the whole package is small compared to an SLR. In addition to the vertical shutter release with the second knurled wheel accessory adds even with another, lying behind thumbwheel and two configurable buttons. In addition, can be virtually "locked" to prevent accidental operation by a switch so the vertical grip. The handle is fitted with a wheel quasi among the top handle, even here the rubber cover of the contacts will disappear in a compartment of the second handle portion and thus can not be lost.
From the handling ago, the OM-D SLR with a side handle in any way stands for, in my view, in most cases, but I will probably use only the smaller stage with the increased grip.
The additional battery pack that can be accommodated in portrait mode part doubles the battery capacity, but will handle only the second battery, the first remains in the camera. Thus, the replacement of the "main battery" of the handle has to be removed. Not a big disadvantage, because this is done quickly and easily, but at SLRs usually the two batteries in the battery grip come then (at least for Canon). Unfortunately I could not test for lack of availability of spare batteries (Release 23 May 2012), which first battery "sucked dry" is. The second handle portion also has a jack for an external 9V power supply, certainly interesting for studio photography.
One thing I have to admit, however, the price is quite steep. However, convinced that clean, very solid workmanship, the interesting concept of two stages and the camera remains splashproof with handle, perhaps the price into perspective a little.
Overall a great accessory, which I can highly recommend.